I think there are 3 reasons why there are many ICOs. One is that more projects that utilise blockchain technology are developing. The second, ICO investment is great way for ICO companies to raise funding. The third, a lot of people have made profit through investments in ICOs and thus more people join in the hopes of 'catching a good break'. This is where scams come in. They take advantage of the hype and new people who want to join and try to scam them.
The important thing is to always do good research before deciding in which ICO to invest.